If you pick up a couple of high pr links such as a 7 or 8 how much of a boost in the serps would you expect and how long does it usually take to see the boost?
Nobody can tell you how much of a boost to expect. It would be based on too many variables...your site's current ranking, the strength of the pages ranking ahead of you, the quality of the PR7/8 links, etc You'd probably see the effects of such a link within a few days.
I won't tout it as anything other than entertainment, but the formula to figure out how much PR gets transferred supposedly looks like this: PRA = 1-d + d*( PRs1/Cs1 + PRs2/Cs2 + PRs3/Cs3 + ... + PRsn/Csn) Where * PRA - Pagerank of a page A * PRsi - Pagerank of page si which links to A; i ranges from 0 to n, n is the total number of all incoming links. The linking page may be any page in internet in any domain. * Csi - Number of outbound links on page si, which has given the link. * d - Damping factor whose value is between 0 and 1. Usually 0.85
Better to have good quality of contents then for google bots to fetch, for surely you will be indexed more often with that backlink.
It's important to check whether then are relevant to your site or not.... but, even one or two backlinks from PR7 sites doesn't change your rankings much.
Well it certainly does help overall, but it will also depend on many other factors. How strong are your competitors and how good your site is doing. If you have a pr1, than having one or two links from a pr7 site might help improve your pr, but only minimal effects on your rankings. But of course sometimes things like this are hard to determine as google's algo is something no one knows about. But it is definitely something that is going to help your website.
It helps if the PR7 and PR8 pages do not have so many outbound links themselves. 1. Your pagerank will go higher (to be either equal or one point less) depending on how many links you have on your page and how many outbound links the PR pages have. 2. Your SERP will increase specially if the niche is the same (relevant pages). Good luck